Update: I took the engine cover off a few weeks ago. I haven't been able to reproduce the fuel smell. A friend stuck his nose in the motor and wasn't able to smell fuel on a cold day and we used a flashlight and didn't see any fuel on the rails.

Still no codes on the Foxwell.

I'm going to hold off on any repairs for now. Maybe I was just being too sensitive to a normal fuel smell now that my mechanic friend, who had done all the work on my X5 since 2003, has passed away.